Euler uses mechanics expressed mathematically to design ships. He adopts Newton's Law of Resistance
(which says that the pressure exerted by a fluid acting against a plane surface is proportional to the
square of the speed, neglecting back pressure) by interpreting it as a statement about differential elements
of surface. He calls this assumption "the common hypothesis" and uses it to calculate the total resistance
by integration. In this way, he arrives at definite answers, often in elegant, explicit forms, that
allow for both quantitative and qualitative conclusions that he develops and interprets clearly.